From BTW in 2008, attempting to describe static test cases in an embedded environment.

The Test Manager and Test Controller could be the same computer or may be different computer/resources. Locality really depends on the system design.

The Test Manager was meant to be something like the test execution tooling provided by Goepel, Asset, JTAG Technologies and others, managing what tests can be applied, when to apply them and collecting the results.

Slides were created at a time when 1149.1 was the clear focus.

Now recognise that there is a need to support dynamic or interactive tests, not just static tests.

{Slide 15}

Added identification of possible points between stack layers where standardisation may be possible.

SVF and STAPL references show their respective scope within the stack. ICL and PDL were not in existence at this time, but otherwise might have been featured.

What about a COTS item where you have little control over its design? Likely that a COTS items would mask out some (or many) of the lower layers. Equates to Gunnar Carlsson's ATCA presentation of a shelf manager sending a "go to yourself" command over the IPMI bus and then querying the result.

If we still think of a stack like this, then we really mean a stack of stacks as move down the hierarchy. This enables a transfer of autonomy (delegation) across hierarchical boundaries.

{Slide 16}

Attempts to build on the stack idea by mapping onto standards and languages and drawing analogies with real-world hierarchy.

Difficulties of creating the decomposition: May be a single board system, a mezzanine assembly of boards, a mini-shelf, a hierarchy within a shelf, multiple shelfs, etc.

There's possibly a version of the stack at each level.

Recognising the need for flow control at every level - PDL arose out of that.

1687 uses abstraction to make all instruments look the same. 1149.1-2013 only details access to the Test Data Register - register level rather than scan chain level. 1687 abstracts the TAP Controller in the device.

For larger systems, they really need a way of describing and using the functionality of the sub-systems. The sub-systems could give finer granularity but not necessarily. This gives control over IP exposure.

Can we develop on the stack diagram? The stack levels are "artificial" and not abstract enough for our current purpose.

We can define hierarchy based on the topology of the system, and have certain primitives that will describe what is available at each level. Scope may be different and less detailed as you go up the hierarchy.

Granularity of control defines what is available at each interface (noting that "interface" has become an overloaded term).

Are the interfaces between layers really "protocols"? Possibly in some cases but the callbacks may be a somewhat more complex than that.

The OSI model (Open System Interconnect, https://en.wikipedia.org/wiki/OSI_model) which we were trying to compare against is fixed in terms of what it's top and bottom represent, while we have a flexible hierarchy. The OSI model also has the concept of each layer providing a wrapper to the layer below, which we cannot emulate.

7. Any Other Business

{Slide 17}

None.

8. Today's Key Takeaways

The stack diagram is of little relevance now and a new form of diagram is required.

Larger systems need a description of, and instructions to use the functionality of its sub-systems (or deeper, depending on what is made available).

External Links

Site Information

NOTE! This site uses cookies and similar technologies.

Click below to accept the use of cookies, or disable cookies in your browser. Learn more

I understand

EU Directive 2009/136/EC requires that a website must obtain prior consent from users before using cookies or similar technologies to gather information from users of the website or storing any data on the user's computer.

Cookies used by this site do not collect any personal information and are simply used to provide a better browsing experience or to maintain essential functionality, such as maintaining a logged-in user's session. The single exception is where a registered user chooses to save their login details for the site using the "Remember me" checkbox, in which case a cookie will be saved to store those details.